MailFlow Sentinel

DNS-based email security assessment. Enter any domain to see SPF, DKIM, DMARC, open relay exposure, and Microsoft 365 direct-send bypass — the complete picture in seconds.

Open MailFlow Sentinel
Reboot Labs
Security Tools
Tools that show what attackers see.
Live DNS Scan
MailFlow Sentinel
Real-time DNS-based security assessment for any domain. See your full email authentication posture — SPF, DKIM, DMARC, open relay exposure, and Microsoft 365 direct-send bypass — exactly as an attacker would.
SPF DKIM DMARC MTA-STS TLS-RPT Open Relay Direct Send BIMI
Analyze a Domain
Analyzers
DMARC Analyzer
Break down every DMARC tag, score your policy, flag issues by severity, and get a hardened record ready to deploy.
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SPF Analyzer
Analyze and repair SPF records. Understand lookup limits, flattening, and exactly what needs to change.
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Email Header Analyzer
Trace delivery hops, verify SPF/DKIM/DMARC authentication, surface spoofing indicators, and get a trust score.
Open
DKIM Analyzer
Look up DKIM public keys by selector, detect weak key sizes, flag revoked keys, and get a plain-English breakdown of every tag.
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Web Security
URL Scanner New
Follow the full redirect chain with status codes, check WHOIS domain age, validate SSL certificates, run Google Safe Browsing, and get a 0–100 risk score with a plain-English verdict.
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